Explosive matrix assembly

ABSTRACT

An explosive matrix includes a grid structure formed from a single length of detonating cord with one set of spaced-apart detonating cord sections lying in one plane that perpendicularly overlays a second set of spaced-apart sections lying in a second plane such that at each section crossing location the crossing consists of no more than two perpendicular sections of detonating cord.

BACKGROUND

1. Field

The present invention relates generally to detonating cord, and moreparticularly to explosive assemblies formed from detonating cord, andfurther, to explosive assemblies forming a grid from detonating cord.

2. Description of the Problem and Related Art

The general concept of using detonating cord to make an explosive matrixas an explosive counter charge is well known, as exemplified by U.S.Pat. Nos. 2,455,354; 3,242,862; 4,768,417; 5,437,230; and 6,182,553; andby the U.S. Navy's Distributed Explosives Technology, described in“Distributed Explosive Technology (DET) Mine Clearance System (MCS) Ex10 Mod 0 Program Life Cycle Cost Estimate for Milestone III” (Jun. 4,1999). These prior designs were created for large military applications.Such applications require significant manpower and financial resources.These prior art explosive matrices must be manufactured well in advanceof their usage. Field assembly is not practical because they are acomplex of multiple lengths of detonating cords joined together.Moreover, due to cost, complexity and time of manufacturing, these priorart explosives matrices have been infeasible for commercial use as ablasting charge. In addition, these prior art explosive matrices areheavy and cumbersome to transport. They use rope or cord to hold thedetonating cord together, creating undesirable bulk and weight.

Another shortcoming of these matrices results from the fact thatdetonating cord detonates linearly from the point of initiation,proceeding therefrom along the cord. Consequently, detonating cord canfail to propagate the detonation wave where the cord makes sharp turns,especially when large grain detonating cord is used. In some prior artdesigns, in order to assure sufficient transfer of the detonating wavebetween intersecting cords, clamps were used at all points ofintersection of detonating cord. This adds further complexity and bulkto these prior art designs.

On the other hand, use of low grain non-propagating detonating cord isnot always possible in prior art explosive matrices. Some prior artdevices initiate at one point, in one direction, and use multiplelengths of detonating cord coupled together, which compromisesreliability. To increase reliability, other explosive matricesincorporate multiple initiation points and multiple lengths ofdetonating cord, again making the design more complex and the assemblymore complicated and expensive.

A later example that addressed many of these shortcomings is taught inU.S. Pat. No. 7,913,624 to the inventor hereof, wherein the explosivematrix assembly permits the construction of explosives counter chargeswhich are more efficient, safer and less costly than the above mentionedprior art explosive matrices. It is typically assembled from a singlelength of detonating cord formed into a grid-like matrix pattern, and asmall number of cable ties and or tape are required to force thedetonating cord into 90 degree angles and to hold the assembly together.However, the detonating cord must be forced into position, which may bemade easier with a field assembly tool, but the design of the fieldassembly tool sometimes creates less than perfect right anglesthroughout the matrix assembly. Furthermore, due to the geometric designof the grid, the matrix will always have intersections that consist offour over-laid sections of detonating cord, while two of the outer sideswill always have three over-laid sections of detonating cord. This makesthe charge non-uniform.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described with reference to the accompanyingdrawings. In the drawings, like reference numbers indicate identical orfunctionally similar elements.

FIG. 1 illustrates two options for an exemplary embodiment of anexplosive matrix assembly using a single length of detonating cords asdisclosed herein;

FIG. 2 illustrates an exemplary embodiment in which two or moreexplosive matrix assemblies may be fastened together;

FIG. 3 depicts a one side member of an exemplary tool useful for formingan explosive matrix assembly as disclosed herein;

FIG. 3A is an end view of an exemplary side member comprising twoidentical members slidingly engaged with one another;

FIG. 4 depicts assembly of an exemplary tool useful for forming anexplosive matrix assembly as disclosed herein;

FIG. 5 depicts an exemplary side member comprising two slidingly engagedmembers showing an exemplary embodiment of an adjustably extendable sidemember;

FIG. 6 depicts assembly of an exemplary tool useful for forming anexplosive matrix assembly as disclosed herein comprised of the exemplaryside members for FIG. 5;

FIG. 7 depicts another exemplary embodiment of an explosive matrixassembly as disclosed herein;

FIG. 8 depicts yet another exemplary embodiment an explosive matrixassembly as disclosed herein;

FIG. 9 is a perspective view of the embodiment depicted in FIG. 8;

FIG. 10 shows another exemplary embodiment of an explosive matrixassembly as disclosed herein;

FIG. 11 illustrates yet another exemplary embodiment of the explosivematrix assembly as disclosed herein.

DETAILED DESCRIPTION

The various embodiments of the disclosed explosive matrix and theiradvantages are best understood by referring to FIGS. 1 through 11 of thedrawings. The elements of the drawings are not necessarily to scale,emphasis instead being placed upon clearly illustrating the principlesof the invention. Throughout the drawings, like numerals are used forlike and corresponding parts of the various drawings.

Furthermore, reference in the specification to “an embodiment,” “oneembodiment,” “various embodiments,” or any variant thereof means that aparticular feature or aspect described in conjunction with theparticular embodiment is included in at least one embodiment. Thus, theappearance of the phrases “in one embodiment,” “in another embodiment,”or variations thereof in various places throughout the specification arenot necessarily all referring to its respective embodiment.

This invention may be provided in other specific forms and embodimentswithout departing from the essential characteristics as describedherein. The embodiments described above are to be considered in allaspects as illustrative only and not restrictive in any manner. Thefollowing claims rather than the description below indicate the scope ofthe invention.

Referring to the drawings, FIG. 1 depicts a preferred embodiment of theexplosive matrix assembly 1. The explosive charge is provided by asingle length of detonating cord 2 that is configured into a first setof at least three parallel straight portions 3 lying in a first plane.There are equal spaces 4, which can altered in size depending upon thedesired size of the overall matrix assembly, but will always be equal toeach other within the same explosives matrix assembly, separating thestraight portions from each other. The detonating cord is furtherconfigured so that there is a second set of at least three more parallelstraight portions 5 that are perpendicular to the first set and lying ina second plane. The second set of straight portions 5 are spaced in amanner similar to the first set of straight portions 3. At one end ofeach parallel straight portions 3, 5 of detonating cord, there is alooped portion 11.

In one embodiment, the detonating cord 2 is further configured so thattwo ends of the detonating cord, 6 a and 6 b, are fastened together withties or tape 7 to form a closed loop 8, or as depicted in Option 2,looped back such that the ends 6 a and 6 b meet and abut one another.This arrangement may be secured with sheet tape or polyethylene foamsheets 22, as depicted in FIG. 7 secures the closed loop.

The explosive initiator 9 can be attached to the detonating cord 2 atany point within the explosives matrix assembly 1. In a preferredembodiment, each of the first and second sets comprises an odd number ofparallel straight portions 3, 5. The reason for the odd number ofparallel straight portions is so that a single looped portion 10 ofdetonating cord may run between the two sets of parallel detonatingcords at a point that is diagonally across from the looped ends 6 a and6 b that are secured to each other.

Typically, the perimeter of each explosive matrix assembly 1 roughlydefines a rectangular panel, the maximum size of which may be madeaccording to the intended function, the minimum size dependent upon thelimited flexibility of detonating cord 2. Alternatively, in the event alarger explosive matrix 1 is desired, assembly panels may be joinedtogether. For example, if the explosive matrix must cover a largersurface area, two or more explosive matrix assemblies are secured to oneanother by cable ties 12, as depicted in FIG. 2. All explosive matrixassembly panels 1 are secured to one another can be initiated by thesame initiator as would be appreciated by those skilled in the relevantarts.

The first step in deploying the claimed invention is for the explosivestechnician to decide how large an explosive matrix 1 area is needed tocompletely cover the surface area required. If the surface area requiredis greater than the surface area of a single explosives matrix assembly1, a sufficient number of explosive matrix assembly panels 1 may be madeand secured to one another by additional cable ties 12 as depicted inFIG. 2.

The explosives technician determines the N.E.W. of the counter chargeneeded to perform the explosives work required. The N.E.W. of the matrixcharge is based on the area of the matrix charge and detonating cordgrain weight. Charts or diagrams may be prepared to provide users of thematrix tool detailed information on the assembly of the matrix charge,the amount of detonating cord needed for a specific size matrix charge,and the N.E.W. for the matrix charge based on the grains per foot ofdetonating cord and the areal size of the matrix charge.

In order to quickly and conveniently assemble the explosive matrix 1 inthe field, an assembly tool 21 may be provided, as shown in FIGS. 3through 6. The assembly tool 21 is designed so that it may be carrieddisassembled to the place where it will be used to deploy the matrix 1.An exemplary assembly tool 21 may include four or eight substantiallyidentical side members 13, an example of which is illustrated in FIG. 3.In the illustrated embodiment, each of the side members 13 comprises anelongated member having at least one castellated edge 28 along a longedge defining a set of recesses 15 and interstitial tabs 22. Thecastellated edge 28 should define at least three, and preferably six, ormore recesses 15, each of which are dimensioned to receive and engagedetonating cord and accommodate the diameter of the cord.

In the illustrated embodiment, the side member 13 terminates in aprotrusion 16 extending from one end 30, with the opposing end 31including a cut-out 17 defined perpendicularly to the long axis of theside member 13. The cut-out 17 is dimensioned to snugly receive theprotrusion 16 comprised in a second side member 13. Bore holes 29 a aredefined through the protrusion 16 and corresponding bore holes 29 b, aredefined in the walls defining the cut-out with the end most holesopening to the outer end of the member 13. As illustrated in FIG. 4, thetool 21 may be assembled by fitting the protrusion 16 of a first member13 into the cut-out 17 of another such that the corresponding bore holes29 a, 29 b align. Fastener pins 14 may then be inserted into the alignedbore holes 29 a, 29 b from the open outer thereof, thus fastening oneend of one member with a counterpart end of a second member, forming aright angle. Assembly of the members 13 is repeated in this manner untila generally rectangular loom results with the castellated edges orientedaway from the center of the tool shape. See FIG. 4. It will beappreciated that the ends of the members 13 may be fastened together inany suitable manner to form a secure perpendicular connection, includinglap joints, hinged couplings, etc. Additionally, although bore holes 29a, 29 b are depicted in the exemplary embodiment in corresponding pairs,more or less holes may be used.

In another embodiment, each side member 13 may comprise two parallelside members, 13 a, 13 b slidingly engaged with one another with theircorresponding castellated edges 28 oriented in the same direction. Thesliding attachment of the two members 13 may be accomplished by anysuitable means known in the art. For example, with reference to FIG. 3A,one member 13 is paired with another member 13, using a sliding dovetailjoint 18 to form a sliding pairs 20 with one member 13 a having anelongated dovetail slot 18 a lengthwise defined in a planar surface andthe second member 13 b having an elongated dovetail pin 18 b extendingfrom the opposing surface thereof. As depicted in FIGS. 5, and 6, thesliding pairs 19 may be assembled in the manner described earliercreating an adjustable assembly tool 21 facilitating the formationlarger explosives matrix assemblies.

Once the matrix tool 21 is assembled it may be used to assemble theexplosive matrix 1, by weaving a length of detonating cord 2 on the toolby inserting the cord into a first recess 15, stretching the cord acrossthe tool and inserting the cord 2 into an opposite second recess 15,bending the cord around the adjacent interstitial tab 22 to insert intoa third recess 15 adjacent the tab 22, and so on until the form depictedin FIG. 1 is complete. The matrix 1 grid is complete with end 6 b backat the starting point.

Once the grid is complete, ties or tape 7 are used to hold ends 6 a and6 b together in a closed loop 8, or abutted together and secured withadhesive sheet tape, or, for example, polyethylene foam sheets 23 withone surface coated with an adhesive which is place on either side of thegrid and then pressed together to bond the grid 1 and sheets 23together, as shown in FIG. 7.

The tool may be removed from the completed matrix assembly 1 by removingthe fasteners 14 allowing the matrix assembly 1 to slide off theassembly tool.

In yet another alternative embodiment, the explosives matrix assembly 1may be combined with a plurality of point explosives 24, such as sheetexplosives, as shown in FIG. 8 and FIG. 9. The explosives matrixassembly 1 only needs to be of sufficient strength to initiate the pointexplosives 24. Because the point explosives 24 are the effectiveexplosives charge, not the explosives matrix assembly 1, a lower grainof cord 2 may be used. Using the matrix assembly 1, point explosives 24are placed at the points in the matrix assembly 1 where lengths ofdetonating cord 2 cross. Initiation of the detonating cord 2 will resultin substantially simultaneous initiation of the point explosives 24creating a shotgun effect with the point explosives 24. Thickness,weight, size, and type of the point explosives 24 may vary dependingupon the needs of the explosives work to be done.

Yet another embodiment employs the explosives matrix assembly 1 toinitiate insensitive blasting agents 25, such as ANFO (Ammonium Nitrateand Fuel Oil) in place of primers, as shown in FIG. 10. By using theexplosives matrix assembly 1 to initiate the blasting agents 25, thecritical diameter of the blasting agent 25 can be reduced below itsnormally accepted critical diameter without a low order detonation. If agreater surface area of the charges is desired or required, matrixassembly 1 panels may be connected together using cable ties or tape 12,as described above. All explosive charges so secured to one another canbe initiated by the same explosives initiator 9.

In a further embodiment and with reference to FIG. 11, the explosivesmatrix assembly 1 e may be connected with other matrix assemblies 1 j,e.g., attaching at least three panels, and preferably five or sixpanels, in a mutually perpendicular shape, i.e., a cube 27, advantageousas an explosives device 26 disruption charge (render safe) to defeatelectronic switches and power sources, as shown in FIG. 11. A low energydetonating cord 2 may be employed in this example. The explosives device26 is either placed in the cube 27 or the cube 27 is placed over theexplosives device. All explosive matrix assemblies 1 so secured to oneanother can be initiated by the same explosives initiator 9.

As described above and shown in the associated drawings, the presentinvention comprises an explosive matrix assembly. While particularembodiments of the invention have been described, it will be understood,however, that the invention is not limited thereto, since modificationsmay be made by those skilled in the art, particularly in light of theforegoing teachings. It is, therefore, contemplated by the appendedclaims to cover any such modifications that incorporate those featuresor those improvements that embody the spirit and scope of the assembly.

I claim:
 1. An assembly formed from detonating cord comprising: a singledetonating cord formed into a grid comprising a first plurality ofspaced-apart lengths lying in a first plane and a second plurality ofspaced-apart lengths lying in a second plane, said first plurality oflengths perpendicularly overlaying said second plurality forming aplurality of crossings, each said crossing consisting of no more thantwo sections of detonating cord, said single detonating cord forming twoclosed loops including a first loop at one corner of the grid and asecond loop at an opposite corner of the grid and wherein said secondloop is formed such that a first end and a second end of said detonatingcord loop back so that said first end and said second end abut oneanother.
 2. The assembly of claim 1, wherein said single length ofdetonating cord comprises two ends, and wherein said grid is formed withsaid two ends abutting each other.
 3. The assembly of claim 2, furthercomprising at least one sheet having at least one surface comprising acoat of adhesive, said at least one surface being adhered to said firstplane.
 4. The assembly of claim 3, wherein said at least one sheet is afirst sheet having at least one surface comprising a coat of adhesiveand a second sheet having at least one surface comprising a coat ofadhesive, said at least one surface of said first sheet being adhered tosaid first plane and said at least one surface of said second sheetbeing adhered to said second plane such that said first and secondadhesive coated surfaces bond together.
 5. The assembly of claim 3,wherein said at least one sheet comprises a polyethylene.
 6. Theassembly of claim 1, further comprising at least one sheet having atleast one surface comprising a coat of adhesive, said at least onesurface being adhered to said first plane.
 7. The assembly of claim 6,wherein said first and second sheets comprise a polyethylene.
 8. Theassembly of claim 1, wherein said grid comprises first and second grids,each of said first and second grids having edges comprising loops formedfrom said single length of detonating cord, and wherein said first gridis attached to said second grid by fastening said loops of one edge ofsaid first grid to said loops of one edge of said second grid.
 9. Theassembly of claim 8, further comprising at least one sheet having atleast one surface comprising a coat of adhesive, said at least onesurface being adhered to said first plane of each said first and secondgrids.
 10. The assembly of claim 8, further comprising at least threegrids, each said grid perpendicularly attached to each other grid. 11.The assembly of claim 10, further comprising at least three sheets eachhaving at least one surface comprising a coat of adhesive, said at leastone surface adhered to at least the first planes of each of said atleast three grids.
 12. The assembly of claim 1, further comprising aplurality of point charges disposed at each crossing of said pluralityof crossings.
 13. The assembly of claim 12, further comprising at leastone sheet having at least one surface comprising a coat of adhesive,said at least one surface being adhered to said first plane.
 14. Theassembly of claim 1, further comprising an ammonium nitrate fuel oilcharge.
 15. The assembly of claim 14, further comprising at least onesheet having at least one surface comprising a coat of adhesive, said atleast one surface being adhered to said first plane.
 16. The assembly ofclaim 1, wherein each end of said parallel portion comprises an openloop.
 17. An explosive matrix assembly comprising a single length ofdetonating cord, said single length of detonating cord formed into afirst set of at least three parallel portions that lie in a first planeand wherein each said parallel portion is spaced apart from the other,and said detonating cord formed into a second set of at least threeparallel portions that lie in a second plane and wherein each saidparallel portion of said second set is spaced apart from the other, andwherein said first set of at least three parallel portionsperpendicularly overlays said second set of at least three parallelportions, said single detonating cord forming two closed loops includinga first loop at one corner of the grid and a second loop at an oppositecorner of the grid and wherein said second loop is formed such that afirst end and a second end of said second loop back so that said firstend and said second end abut one another.
 18. The explosive matrixassembly of claim 17, further comprising at least one sheet having atleast one surface comprising a coat of adhesive, said at least onesurface being adhered to said first plane.
 19. The explosive matrixassembly of claim 17, further comprising a second explosive matrixassembly fastened to said explosive matrix assembly.
 20. The explosivematrix assembly of claim 19, further comprising a plurality of explosivematrix assemblies mutually perpendicularly attached.
 21. The explosivematrix assembly of claim 17, wherein each of said first set and saidsecond set comprises and odd number of parallel portions.
 22. Theassembly of claim 17, wherein each end of said parallel portioncomprises an open loop.